Process for the oligomerization of olefins and a catalyst thereof

ABSTRACT

Olefins may be oligomerized to a desired oligomer and configuration of the oligomer by utilizing a catalyst which comprises a porous support containing a catalytically effective amount of an hydrate of an iron group metal salt in which the mole ratio of water of hydration to iron group metal is greater than 0.5:1 in combination with a catalytically effective amount of an alkyl aluminum compound and an aluminum halide.

BACKGROUND OF THE INVENTION

The oligomerization of olefins is known in the art, such oligomerizationprocesses being effected by treating olefinic hydrocarbons with certaincatalysts to obtain various oligomers which will find a useful functionin the chemical art. One type of catalyst which may be employed for thisparticular type of reaction comprises a supported metal compound. Forexample, U.S. Pat. No. 3,562,351 discloses a method for dimerizingolefins utilizing a supported catalyst which has been prepared byimpregnating a suitable support with a salt solution of a Group VIIImetal followed by a heat treatment in an inert atmosphere at atemperature less than that which is required to form a metal oxide butwhich will form a complex on the surface of the solid support. Followingthis, the catalyst is activated by treatment with an organometalliccompound. U.S. Pat. No. 3,483,269 describes a catalyst useful foroligomerizing lower olefins which comprises a π-allyl nickel halidesupported on an acidic inorganic oxide support. If so desired, thesupport may have been optionally treated with an alkyl aluminumcompound. U.S. Pat. No. 3,592,869 also describes a catalyst which isuseful for the oligomerization of olefins. A divalent nickel compoundand an alkyl aluminum compound are contacted with an olefinic compound.The resulting mixture is then used to impregnate an inorganic refractoryoxide support. Another patent, namely U.S. Pat. No. 3,644,564, describesa catalyst for the oligomerization of ethylene which comprises an organoaluminum-free reaction product of a nickel compound which is an atom ofnickel in complex with an olefinically unsaturated compound and afluorine-containing ligand. The catalysts are typically formed in situ.U.S. Pat. No. 3,679,772 describes a process for reacting monoolefinswith diolefins, the catalyst for such a reaction comprising a complex of(1) nickel, (2) a Group VA electron donor ligand such as anorganophosphine, (3) a nonprotonic Lewis acid and (4) a reducing agentwhich itself may be a Lewis acid, all of which are composited on anacidic silica-based support.

U.S. Pat. No. 3,697,617 describes an oligomerization process involvingthe use of a catalyst comprising a complex of nickel with achloro-containing electron donor ligand such as chlorodiphenylphosphinecombined with a nonprotonic Lewis acid which is capable of forming acoordination bond with nickel and a reducing agent capable of reducingnickel acetylacetonate to an oxidation state less than 2. This complexmay be composited on a solid support comprising an acidic silica-basedmaterial such as silica-alumina. The Lewis acid and the reducing agentmay comprise the same compound as, for example, ethyl aluminum sesquichloride. U.S. Pat. No. 3,663,451 describes a catalyst which is obtainedby reacting a transition metal halide such as nickel halide with acarrier to give a carrier-metal bond. This product is then reacted witha ligand such as a phosphine or β ketone and finally activated bytreatment with an aluminum alkyl or chloro alkyl.

U.S. Pat. No. 3,755,490 describes the polymerization of an olefinutilizing a catalyst comprising nickel, a Group VA electron donorligand, a Lewis acid, and a reducing agent on a solid acidicsilica-based support. U.S. Pat. No. 3,954,668 is drawn to anoligomerization catalyst comprising a nickel compound, achloro-containing electron donor ligand, or a phosphorous compound, anonprotonic Lewis acid reducing agent which is capable of reducingnickel acetylacetonate to an oxidation state of less than 2 and which isalso capable of forming a coordination bond with a nickel. U.S. Pat. No.3,170,904 speaks to a catalyst which is useful for polymerizationcomprising a large surface area metal of Groups VIIA or VIII of thePeriodic Table, boron trifluoride etherate, an organometallic compoundof Groups I, II, III or IV or a halo derivative of an organometalliccompound of Groups II, III or IV or a hydride of a metal of Groups I, IIor III. The large surface area metal which comprises one component ofthis catalyst is in metallic form as, for example, Raney nickel. If sodesired, the catalyst may be composited on a diatomaceous earth carrier.In like manner, U.S. Pat. No. 3,170,904 discloses a catalyst whichcomprises (A) a carrier-supported nickel or cobalt oxide which has beenprepared by impregnating the carrier with the hydroxide, organic acidsalt, inorganic acid salt, followed by oxidation in the presence ofoxygen or a combination of nitrogen and oxygen; (B) a boron, titanium,zirconium, or vanadium halide; and (C) an alkyl metal or alkyl metalhalide. In addition to these patents, British Patent No. 1,390,530describes an oligomerization catalyst which has been prepared bythermally pretreating a metal oxide carrier material followed byreacting with a halogen-containing organo-aluminum compound andthereafter in a step-wise fashion, impregnating this product with adivalent nickel or cobalt complex at temperatures ranging from -50° to150° C.

As will hereinafter be shown in greater detail, the oligomerization ofolefinic hydrocarbons may be accomplished by treating said olefins inthe presence of a catalyst which has been prepared in a manner such thatthe catalyst will remain active and stable for a relatively long periodof time and, in addition, will provide products which possess a desiredconfiguration with respect to the branching or minimal branching of thechain.

BRIEF SUMMARY OF THE INVENTION

This invention relates to a catalytic composite which is useful for theoligomerization of olefinic hydrocarbons. More specifically, theinvention is concerned with a catalyst composite and a process for theoligomerization of olefinic compounds, particularly olefinichydrocarbons, whereby the use of the catalytic composite will result inthe obtention of selective oligomers of the olefinic feed stock.

The term "polymerization" has a relatively broad meaning in the chemicalart. Although it is generally referred to as the preparation ofrelatively high molecular weight polymers, that is polymers possessingmolecular weights of greater than 50,000 or more, it may also refer tolow molecular weight polymers, that is, polymers possessing molecularweights lower than 50,000. In contradistinction to this, the term"oligomerization" refers to polymeric compounds in which the moleculesconsist of only a relatively few monomeric units and thus would includedimerization, trimerization or tetramerization.

Many olefinic hydrocarbons which contain from 4 to about 12 carbon atomsin the chain are utilized in various industries in many ways. Forexample, dimers of propylene regardless of the amount of branching maybe used to improve the octane number of motor fuels which are utilizedin internal combustion engines utilizing gasoline as the fuel thereof.The presence of these compounds in a motor fuel such as gasoline willimprove the octane number of the fuel to a high level, thus enabling thegasoline to be utilized in combustion engines in an unleaded state.Other uses for dimers containing 6 carbon atoms would be in thesynthesis of flavors, perfumes, medicines, dyes and resins. Another useof an oligomer would be found in the dimerization product of butene inwhich the dimer which possesses a relatively straight chainconfiguration with a minimum of branching such as one methyl substituenton the chain would be as an intermediate in the production of aplasticizer. The plasticizer, when added to a plastic will facilitatecompounding and improve the flexibility as well as other properties ofthe finished product. Likewise, a trimer of butene or a dimer of hexenein which the olefin contains 12 carbon atoms may be used as anintermediate in various organic syntheses such as in the preparation ofdetergents, lubricants, additives, plasticizers, flavors, perfumes,medicines, oils, dyes, etc. In addition, linearized oligomers containing12 or more carbon atoms, upon hydrogenation, provide excellent dieselfuels.

It is therefore an object of this invention to provide a catalyst forthe oligomerization of olefinic hydrocarbons.

A further object of this invention is to provide a specific catalystsystem which may be used in a process for the oligomerization ofolefinic hydrocarbons whereby selective oligomers may be obtainedthereby.

In one aspect an embodiment of this invention resides in a catalyticcomposite comprising a combination of a catalytically effective amountof an alkyl aluminum compound on a porous support containing acatalytically effective amount of hydrate of an iron group metal salt inwhich the mole ratio of water of hydration to iron group metal isgreater than 0.5:1.

Another embodiment of this invention is found in a process for theoligomerization of an olefinic hydrocarbon which comprises treating saidhydrocarbon in the presence of a catalyst comprising a combination of acatalytically effective amount of an alkyl aluminum compound compositedon a porous support containing a catalytically effective amount ofhydrate of an iron group metal salt in which the mole ratio of water ofhydration to iron group metal is greater than 0.5:1, at oligomerizationconditions, and recovering the resultant oligomer.

A specific embodiment of this invention is found in a catalyticcomposite comprising a combination of a catalytically effective amountof diethyl aluminum chloride on an alumina support which contains acatalytically effective amount of nickel hydrate, the mole ratio ofwater of hydration to iron group metal being in a range of from about0.5:1 to about 6:1 prior to reaction with said diethyl aluminumchloride, said diethyl aluminum chloride being present in a mole ratioin the range of from about 0.05:1 to about 6:1 moles of diethyl aluminumchloride per mole of nickel.

Another specific embodiment of this invention is found in the processfor the oligomerization of an olefinic hydrocarbon which comprisestreating propylene in the presence of a catalyst comprising acombination of a catalytically effective amount of diethyl aluminumchloride on an alumina support which contains a catalytically effectiveamount of nickel hydrate, the mole ratio of water of hydration to irongroup metal being in a range of from about 0.5:1 to about 6:1 prior toreaction with said diethyl aluminum chloride, said diethyl aluminumchloride being present in a mole ratio in the range of from about 0.05:1to about 6:1 moles of diethyl aluminum chloride per mole of nickel at atemperature in the range of from about -20° to about 120° C. and apressure in the range of from about 350 to about 1000 pounds per squareinch gauge, and recovering the resultant oligomer comprising a mixtureof hexene, methylpentene and dimethylbutene.

Other objects and embodiments will be found in the following detaileddescription of the invention.

DETAILED DESCRIPTION OF THE INVENTION

As hereinbefore set forth, the present invention is concerned with acatalyst composite which may be utilized for the oligomerization ofolefins and to a process which employs the catalyst. Heretofore, thepreparation of a catalytic composite which may be used for thepolymerization or oligomerization of olefinic compounds was relativelydifficult inasmuch as several relatively expensive compounds wererequired as components of the composite. In contradistinction to this,the catalytic composite of the present invention is relatively easy toprepare and, in addition, employs compounds which are less expensivethan the components of the other catalyst. The final catalytic compositeof the present invention will possess a high activity and will be stableover a relatively long period of time. In addition to these desiredattributes, the catalyst will also produce a high yield of dimerproducts, especially from C₃ and C₄ olefins as compared to trimer andtetramer products. The dimer products produced by the oligomerization ofpropylene or the n-butenes will possess a high percentage of linearcompounds, that is, n-hexenes and n-octenes and also a high percentageof dimers which contain only one methyl substituent; more highlybranched oligomers being minority products. The propylene dimers whichare produced by the process of the present invention all possess highoctane numbers regardless of the branching, and thus are excellentoctane blending components. In addition, the n-butene dimers areexcellent as intermediates in the preparation of plasticizers.

The catalytic composite of the present invention will comprise acombination of a catalytically effective amount of an alkyl aluminumcompound on a porous support which contains a catalytically effectiveamount of hydrate of an iron group metal salt. In addition, if sodesired, the catalytic composite can also contain, in combinationtherewith, a catalytically effective amount of an aluminum halide. Inthe preferred embodiment of the invention, the hydrate of an iron groupmetal salt will be obtained from a soluble salt of nickel or cobalt suchas, for example, nickel nitrate, nickel hydroxide, nickel bromide,nickel chloride, nickel fluoride, nickel acetate, cobaltic chloride,cobaltus acetate, cobaltus ammonium chloride, cobaltus bromide, cobaltusfluoride, cobaltus perchlorate, cobaltus sulfate, etc. The poroussupport upon which the iron group metal hydrate is impregnated willinclude inorganic metal oxides such as alumina, silica, mixtures ofoxides such as alumina-silica, alumina-zirconia-magnesia, etc. orcrystalline aluminosilicates which are commonly known as zeolites.

The other components of the catalytic composite will comprise alkylaluminum compounds such as dimethyl aluminum chloride, diethyl aluminumchloride, dipropyl aluminum chloride, dimethyl aluminum bromide, diethylaluminum bromide, dipropyl aluminum bromide, dimethyl aluminum iodide,diethyl aluminum iodide, dipropyl aluminum iodide, etc. In addition, thealuminum halide which may be used to form a component of the catalyticcomposite in conjunction with the alkyl aluminum compound will includealuminum chloride, aluminum bromide, aluminum iodide, etc. It is to beunderstood that the aforementioned list of iron group metal compounds,porous supports, alkyl aluminum compounds and aluminum halides are onlyrepresentative of the class of compounds which may be employed to formthe catalytic composite of the present invention, and that saidinvention is not necessarily limited thereto.

The oligomerization catalyst of the present invention may be prepared insuch a manner so as to provide the finished catalyst with certaincharacteristics with regard to the selectivity of olefins obtained bythe reaction of an olefin in the presence of said catalyst as well as aspecificity of the product so obtained. The catalyst composite isprepared by impregnating a porous support of the type hereinbefore setforth with a simple divalent iron group metal salt such as, for example,nickel nitrate, preferably from an aqueous solution. After impregnationof the porous support such as alumina, which is effected at ambienttemperature and atmospheric pressure, the impregnated support is thensubjected to a thermal treatment. By varying the temperature of thethermal treatment, it is possible to obtain a catalyst composite whichwill provide a greater selectivity to dimer products resulting from theoligomerization of the olefin in contrast to trimer and tetramerproducts than are obtained when using other conventional oligomerizationcatalysts. The thermal treatment of the impregnated support ispreferably effected in a range of from about 350° to about 450° C., thepreferred thermal treatment temperature being in a range of from about340° to about 360° C. The thermal treatment of the catalyst basecontaining the impregnated iron group metal salt in hydrate form willresult in a weight loss due to a loss of water of hydration from themetal salt. In the preferred embodiment of the invention, the mole ratioof water of hydration to iron group metal following the thermaltreatment will be greater than 0.5:1 and preferably in a range of fromabout 0.5:1 to about 6:1.

Following the thermal treatment, the iron group metal impregnatedcatalyst base is then treated with an alkyl aluminum compound whereinthe activated solution will produce a catalyst of maximum activity. Thetreatment of the base with the activating agent is also effected atambient temperature and atmospheric pressure utilizing a solution of thealkyl aluminum compound dissolved in an organic solvent such as benzene,toluene, the xylenes, etc. In the preferred embodiment of the invention,in addition to the alkyl aluminum compound which may be of the typehereinbefore set forth in greater detail, an aluminum halide compoundmay also be used in this step. The addition of the impregnated base tothe organic solution will result in an exothermic reaction and afterthorough admixture, the solution is allowed to return to roomtemperature. The solvent may then be removed by conventional means suchas decantation, evaporation, etc. and the catalyst thereafter washedwith an organic solvent to remove residue or trace portions of unwantedcompounds. Thereafter, the catalyst may then be dried by purging withnitrogen, and recovered. In the finished composite, the alkyl aluminumcompound is present in the composite in a mole ratio in the range offrom about 0.05:1 to about 6:1, preferably in a range of from about0.1:1 to about 1:1, moles of alkyl aluminum compound per mole of irongroup metal, the latter being present in said composite, on an elementalbasis, in an amount in the range of from about 1% to about 20% by weightof the composite, and preferably in an amount in a range of from about1% to about 10%.

As will hereinafter be shown in greater detail, by preparing a catalystwhich possesses the various components in the finished composite in moleratios or weight percent within the ranges hereinbefore set forth, it ispossible to selectively oligomerize olefin compounds containing fromabout 2 to about 6 carbon atoms with a concurrent obtention of desirableisomers in each of the oligomer products. In addition, by utilizing analuminum halide as a component of the catalyst composite in addition tothe alkyl aluminum compound, it is possible to obtain a catalystcomposite which will be more stable and more active in the conversion ofolefins to oligomers than are catalysts which do not contain thiscompound.

As an example of how the catalyst composite of the present invention maybe prepared, a predetermined amount of a porous base such as alumina,silica, silica-alumina, aluminosilicate, etc. which may be in the formof spheres, pellets, rods, etc. may be prepared in an appropriateapparatus such as an evaporator along with an aqueous solution of ahydrated salt of an iron group metal. The mixture may be thoroughlyadmixed and following this, the apparatus heated to form the desirediron group metal impregnated base. The impregnated base may then beplaced in a heating apparatus such as a tube furnace and treated withair while bringing the catalyst to a temperature of about 250° C. Theheating is accomplished at a relatively slow rate and after thedetermined temperature has been reached, it is maintained thereat for anadditional period of time which may range from about 2 to about 4 hoursor more in duration. The calcination of the catalyst base is theneffected by increasing the temperature to a predetermined level andmaintaining thereat for a period of time sufficient to bring the moleratio of water of hydration present in the iron group metal salt to adetermined level which is preferably in an excess of about 5:1 moles ofwater of hydration per mole of iron group metal.

After allowing the calcination to proceed for this predetermined periodof time, heating is discontinued and the catalyst base which containsfrom about 1% to about 20% by weight of iron group metal is allowed tocool. The cooled base may then be admixed with a solution of an alkylaluminum compound and an aluminum halide dissolved in an organicsolvent. As previously discussed, the resulting reaction is exothermicin nature and after allowing the heat to dissipate, the resultingadmixture is thoroughly stirred and allowed to stand for a period oftime which may range from about 1 to about 100 hours or more induration. At the end of this period, the organic solvent is removed bydecantation, filtration, centrifugation, etc. and the solid catalyst iswashed to remove any unreacted material. After washing, the catalyst isthen dried in an inert atmosphere such as that provided for by thepresence of nitrogen, and recovered.

The oligomerization of olefins containing from 2 to about 6 carbon atomssuch as ethylene, propylene, butene-1, butene-2, pentene-1, pentene-2,pentene-3 may then be effected by treating the oligomer in the presenceof the catalyst at oligomerization conditions which will include atemperature in the range of from about -20° C. to about 120° C., thepreferred range being from about 30° to about 80° C., and a pressure inthe range of from about 350 to about 1000 pounds per square inch gauge(psig). The pressure which is utilized may be the autogenous pressureprovided for by the feedstock, if in gaseous phase, or, the feedstockmay supply only a partial pressure, the remainder of said pressure beingprovided by the introduction of an inert gas such as nitrogen, helium,argon, etc. into the reaction zone.

It is contemplated within the scope of this invention that theoligomerization process may be effected in either a batch or continuoustype operation. For example, when a batch type operation is employed, aquantity of the novel catalyst composite of the present invention may beplaced in an appropriate apparatus such as, for example, an autoclave ofthe rotating, mixing or stirring type. If the olefinic feedstock is ingaseous form, the autoclave is sealed and the feedstock comprising theolefinic hydrocarbon or a mixture of olefinic and paraffinic hydrocarbonor similar carbon atom length are charged to the reactor until thedesired operating pressure has been attained. The apparatus is thenheated to the desired operating temperature and maintained thereat for apredetermined period of time which may range from about 1 to about 6hours or more in duration. At the end of this period of time, heating isdiscontinued and after the apparatus and contents thereof have returnedto room temperature, the excess pressure is discharged and the autoclaveis opened. The reaction product is recovered, separated from thecatalyst by conventional means such as decantation, filtration,centrifugation, etc. and, if so desired, subjected to fractionaldistillation whereby the various isomers may be separated, one fromanother, and stored. Conversely, if so desired, the reaction productcomprising a mixture of isomers may be recovered and stored per sewithout separating the various isomeric fractions which are present inthe product mixture.

In the event that the olefinic charge stock is in liquid form, it may becharged to the reactor which is thereafter sealed and pressured to thedesired operating pressure by the introduction of an inert gas of thetype hereinbefore set forth. The remainder of the operations to obtainthe desired oligomer product is carried out in a manner similar to thatpreviously described.

When utilizing a continuous method of operation to obtain the desiredoligomer products, a quantity of the catalyst composite is placed in anappropriate apparatus. The feedstock comprising the olefinic compound iscontinuously charged to this reactor which is maintained at the properoperating conditions of temperature and pressure. As in the case of thebatch type operation, the desired operating pressure may be provided forby the olefinic hydrocarbon itself or by the addition of a heated inertgas. After passage through the reactor for a predetermined period oftime, the reactor effluent is continuously discharged and the reactionproduct may be recovered and passed to storage or it may be passed to adistillation apparatus whereby separation of the various isomers andoligomers may be effected. Any unreacted olefinic hydrocarbon which isrecovered from the reactor effluent may be recycled back to the reactorto form a portion of the feed charge.

Inasmuch as the catalyst composite of the present invention is in solidform, the continuous method of operation for obtaining the desiredoligomers of the olefinic hydrocarbons may be effected in various typesof operations. For example, in one type of operation, the catalyst ispositioned as a fixed bed in the reaction zone and the olefinicfeedstock is charged so that it passes over the catalyst bed in eitheran upward or downward flow. Another type of continuous operation whichmay be employed comprises the moving bed type of operation in which thecatalyst bed and the feedstock are passed through the reaction zoneeither concurrently or countercurrently to each other. In addition tothe fixed or moving bed type of operation, it is also contemplated thatthe slurry type of operation may be employed, especially when theolefinic hydrocarbon feedstock is in liquid form. When this type ofoperation is employed, the catalyst is charged to the reactor as aslurry in the olefinic feedstock.

Examples of oligomers of olefinic compounds which may be obtained whenutilizing the catalyst composite of the present invention will includen-butene, isobutene, n-hexene, methyl pentene, dimethyl butene,n-octene, the isomeric heptenes, dimethyl hexenes, n-dodecene, theisomeric methyl undecenes, dimethyl decenes, etc. As was previouslystated, the oligomer products which are obtained in the process of thisinvention will comprise, in the main, the dimers of the particularolefinic compound which was employed as the feedstock, thus, forexample, when employing ethylene as the feed, the reaction product willcomprise mostly C₄ olefins; when employing propylene as the feedstock,the reaction product will comprise mostly C₆ olefins; and when employingbutene as the feedstock, the reaction product will comprise mostly C₈olefins. Thus, the catalyst composite of the present invention willresult in products which find particular uses in the finished product.

The following examples are given for purposes of illustrating the novelcatalyst composites of the present invention, methods for preparingthese composites and a process for utilizing these composites. However,it is to be understood that these examples are merely illustrative innature and that the present invention is not necessarily limitedthereto.

EXAMPLE I

A catalyst was prepared by impregnating 250 cc of alumina spheres withan aqueous solution of 250 cc of water containing 34.6 grams of nickelnitrate hexahydrate. The impregnation was effected in a rotaryevaporator in which the mixture was rolled for a period of 0.5 hourswith no heat. The evaporator was then heated with steam for a period oftwo hours at which time the water phase was evaporated. The catalystbase was then loaded into a tube furnace and air was passed through thecatalyst bed at a rate of 600 cc per minute. Following this, thetemperature of the bed was raised to 250° C. during a period of twohours and thereafter the bed was maintained at this temperature for anadditional period of three hours. At the end of this time, the bed wasallowed to cool to room temperature and thereafter the bed was calcinedby raising the temperature to 400° C. during a two-hour period. The 400°C. calcination temperature was maintained for an additional period ofthree hours following which heating was discontinued and the impregnatedbase was recovered.

An activating solution was prepared by adding 3.91 grams of anhydrousaluminum chloride to 174 cc of toluene in a 500 cc flask along with 18grams of diethyl aluminum chloride as a 50 weight percent solution intoluene. The addition of the solutions was accomplished in a glove boxwhile maintaining a nitrogen atmosphere for the addition. After thoroughadmixture, the solution was allowed to stand for a period of 3.5 hourswith intermittent swirling thereof.

The impregnated base was placed in a 500 cc flask along with 240 cc oftoluene. The activating solution containing the aluminum chloride anddiethyl aluminum chloride was slowly added during a period of 15 minutesto avoid overheating of the catalyst due to the exothermic nature of thereaction. After addition of the activating solution to the support, theresulting solution was slightly warm with a concurrent emission of somegas bubbles. The solution was allowed to stand for a period of 18.5hours at the end of which time the impregnated liquors were decanted andthe catalyst was washed with six portions of isopentane utilizing 100 to115 cc per wash. The resulting catalyst composite was then allowed todry in a glove box under nitrogen atmosphere until it becamefree-flowing. This catalyst was designated as "A."

EXAMPLE II

A second catalyst composite was prepared in a manner similar to that setforth in Example I above. The catalyst base comprised 250 cc of aluminacontaining 5% by weight of nickel, said impregnated base again beingcalcined at a temperature of 400° C. The catalyst support was placed ina 500 cc flask along with 250 cc of toluene. A solution prepared in amanner similar to that set forth in Example I above from 18 grams ofdiethyl aluminum chloride as a 50 weight percent solution in toluene and174 cc of toluene (no aluminum chloride being present) was slowly addedduring a period of 15 minutes to prevent overheating of the catalyst.Again, it was noted that the solution was slightly warm following theaddition with the evolution of some gas bubbles. The solution was againallowed to stand for a period of 18.5 hours following which theimpregnation liquors were decanted and the solid catalyst washed withsix portions of isopentane using 115 to 120 cc per wash. This catalystwas then allowed to dry in a glove box under nitrogen until it wasfree-flowing in nature. The catalyst was designated as "B."

EXAMPLE III

The catalysts prepared according to the methods set forth in Examples Iand II above were utilized in the oligomerization of butene-1. Theoligomerization was effected by placing 100 cc of the catalysts in atubular reactor having an outside diameter of 0.5". A feedstockcomprising a mixture of 60% butene-1 and 40% n-pentane was charged tothe reactor at a LHSV of 1.0 hours⁻¹ based upon the olefin. Reactionconditions which were employed for the oligomerization included areactor inlet temperature of 35° C. and a pressure of 700 psig. Theoligomerization was allowed to proceed for a period of 100 hours,samples being taken and analyzed at various points during the reactionperiod. The results of these analyses are set forth in Table 1 below:

                  TABLE 1                                                         ______________________________________                                        Hours        Catalyst A                                                                              Catalyst B                                             ______________________________________                                                   Unreacted Olefin %                                                 20           --        28                                                     30           11.5      --                                                     55           12.5        31.5                                                 75           12.0      --                                                     80           --          32.5                                                 100          13.0        37.5                                                            Butene Conversion %                                                30           93        79                                                     55           92        73                                                     80           93        71                                                     100          91        69                                                     ______________________________________                                    

EXAMPLE IV

To illustrate the difference in selectivity factors which may beobtained by calcining the impregnated catalyst base at varioustemperatures, three different catalysts were prepared. The calcinationof the alumina base was effected in a manner similar to that set forthin Example I above utilizing a nickel nitrate hydrate solution whichresulted in a base containing 5% by weight of nickel. After drying theimpregnated base at a temperature of 250° C. for a period of threehours, the base was then calcined by raising the temperature at whicheach base was calcined to different levels. After calcining the bases atthe different temperatures, the bases were then treated with anactivating solution of diethyl aluminum chloride and aluminum chloridein a manner also similar in nature to that set forth in Example I aboveto prepare the three finished catalyst composites.

The three catalyst bases were calcined at temperatures of 350° , 400° ,and 450° C. respectively, the finished catalyst composites whichresulted from the use of these bases being labeled C, D and Erespectively. The finished catalyst composites were then utilized in anoligomerization reaction involving a feedstock comprising 60% butene-2and 40% n-butane, said reaction being effected at a reactant inlettemperature of 70° C., a pressure of 700 psig and an olefin LHSV of 0.6for C and 1.0 for D and E hrs.⁻¹.

The weight loss which each catalyst base underwent during thecalcination period as well as the selectivity to isomeric octenes at aconversion rate of 50% of the butene-2 are set forth in Table 2 below:

                  TABLE 2                                                         ______________________________________                                                     Catalyst                                                                      C         D      E                                               ______________________________________                                        Calcination Temp. °C.                                                                 350         400    450                                         Wt. Loss %     2.9         1.5    0.8                                         C.sub.8.sup. = Selectivity                                                                    88          76     54                                         ______________________________________                                    

It is apparent from the above Table that the temperature at which theimpregnated catalyst base is calcined will have an effect upon theselectivity of the olefin oligomerization process, the lower calcinationtemperature providing the greatest percentage of selectivity.

In like manner, it is also evident from the results obtained when usingtwo catalysts, one of which did not contain an aluminum halide as onecomponent thereof, that a catalyst composite comprising a combination ofa catalytically effective amount of an alkyl aluminum compound and analuminum halide on a porous support which contains a catalyticallyeffective amount of an iron group metal hydrate will result in obtaininga greater amount of oligomer than will be obtained when utilizing acatalyst which does not contain the aforesaid aluminum halide.

EXAMPLE V

An oligomerization catalyst was prepared by impregnating 250 cc ofalumina spheres with an aqueous solution of 250 cc of water containing34.6 grams of nickel nitrate hexahydrate. The impregnation was effectedin a rotary evaporator in which the mixture was rolled for a period of0.5 hours without heating, followed by heating with steam for a periodof two hours at which time the water was evaporated. The catalyst basewas then calcined in a manner set forth in the above example by loadinginto a tube furnace, heating to 250° C. for a period of two hours,cooling to room temperature followed by raising the temperature to 400°C. and maintaining the temperature for a period of three hours.

An activating solution was prepared by adding 1.5 grams of anhydrousaluminum chloride to 62 grams of toluene in a 500 cc flask along with5.45 grams of diethyl aluminum chloride in 33 cc of hexane. The additionof the solutions was effected in a glove box while maintaining anitrogen atmosphere and after thorough admixture, the solution wasallowed to stand for a period of 3.5 hours.

To prepare the desired catalyst, 125 cc of the catalyst base was placedin a 500 cc flask along with 125 cc of toluene. The activator solutionwas then slowly added to the catalyst base over a period of 30 minutesin order to avoid overheating. The solution was warm and in addition,gas bubbles were formed after the addition. After allowing the solutionto stand for a period of 18 hours, the solvents were decanted and thecatalyst was washed with six 80 cc portions of isopentane. The catalystcomposite was allowed to dry in a glove box under a nitrogen atmosphereand designated as "F."

EXAMPLE VI

In this example, 250 cc of alumina spheres were impregnated with anaqueous solution of 250 cc of water containing 34.6 grams of nickelnitrate hexahydrate in a manner similar to that set forth in Example Vabove. The catalyst base was then divided into six separate portions,loaded into a tube furnace, and treated in a manner similar to that setforth in the above example by calcining at a temperature of 400° C. fora period of three hours.

Six batches of activating solution were prepared by adding 3.9 grams ofanhydrous aluminum chloride and 16.9 grams of diethyl aluminum chlorideas a 50 wt. % solution and 39 cc of toluene to 174 cc of toluene. Themixing was effected in a glove box under a nitrogen atmosphere and after3.5 hours all of the solid had dissolved. Each batch of the solution wasused to activate the six 250 cc catalyst bases prepared according to theabove paragraph. Each portion of the catalyst base was placed in a 500cc flask along with 250 cc of toluene, the addition of the activatorsolution being accomplished over a 15 minute period. After allowing thesolution to stand for a period of 18.5 hours, the solvent was decantedand each catalyst was washed with six 100-115 cc portions of isopentane.Thereafter, the catalyst portions were allowed to dry in a glove boxunder nitrogen and combined, this catalyst being designated "G."

EXAMPLE VII

To vary the ratio of nickel to aluminum halide, a catalyst was preparedby impregnating 250 cc of alumina spheres with an aqueous solutioncomprising 250 cc of water containing 71.3 grams of nickel nitratehexahydrate. After impregnation, the catalyst base was treated in amanner similar to that hereinbefore set forth and loaded into a tubefurnace during which air was passed through the catalyst bed at a rateof 600 cc per minute. Following this, the temperature of the bed wasraised to 250° C. during a period of two hours and maintained thereatfor an additional period of three hours. At the end of this time, thebed was allowed to cool to room temperature and thereafter, the catalystwas calcined by raising the temperature of the furnace to 350° C. duringa two-hour period. The 350° C. calcination temperature was maintainedfor an additional period of two hours following which heating wasdiscontinued and the impregnated base was recovered.

An activating solution was prepared by adding 5.87 grams of anhydrousaluminum chloride to 80 cc of toluene in a 500 cc flask along with 58.1cc of a 50 wt. % diethyl aluminum chloride in a toluene solution (27.0grams of diethyl aluminum chloride). A portion (125 cc) of theimpregnated catalyst base was then placed in a 500 cc flask along with120 cc of toluene. The activating solution was slowly added during aperiod of 15 minutes and allowed to stand for 18.5 hours. At the end ofthis time, the impregnating liquors were decanted and the catalyst waswashed with six portions of isopentane utilizing 100 to 115 cc per wash.The catalyst composite was allowed to dry in a glove box under anitrogen atmosphere until it became free-flowing, this catalyst beingdesignated "H."

EXAMPLE VIII

Catalysts F, G and H which were prepared according to the above exampleswere used in a propylene oligomerization test. Each catalyst in anamount of 50 cc was placed in a tube reactor and a charge comprising 90%by weight of propylene and 10% by weight of propane was charged to eachreactor at olefin Liquid Hourly Space Velocities ranging from 2.0 to 3.0hours⁻¹. The reactors were maintained at a pressure of 700 pounds persquare inch gauge while the bath temperatures were maintained at from35° to 50° C. A fractionation column was used to separate unreacted C₃'s from the oligomers and a portion of the unreacted C₃ 's (bothpropylene and propane) was recycled to the reactor inlet. The results ofthe runs are set forth in Table 3 below:

                  TABLE 3                                                         ______________________________________                                                  Catalyst "F"                                                                           Catalyst "G"                                                                             Catalyst "H"                                    ______________________________________                                        Run Length (hrs.)                                                                         1385       1042       36                                          Overall Propylene                                                                         88.7-99.8  92.6-99.9  61.3-91.7                                   Conversion (wt. %)                                                            C.sub.6.sup. = selectivity                                                                70.7-81.5  77.4-92.6  --                                          (wt. %)                                                                       Research Octane                                                                           95-96      95-96      --                                          No.                                                                           Motor Octane No.                                                                          80-81      80-81      --                                          ______________________________________                                    

I claim as my invention:
 1. A catalytic composite comprising acombination of a catalytically effective amount of an alkyl aluminumcompound on a porous support containing a catalytically effective amountof hydrate of an iron group metal salt in which the mole ratio of waterof hydration to iron group metal is greater than 0.5:1.
 2. The catalyticcomposite as set forth in claim 1 further characterized in that saidcomposite contains in combination therewith a catalytically effectiveamount of an aluminum halide.
 3. The catalytic composite as set forth inclaim 1 in which said iron group metal is present in said composite, onan elemental basis, in an amount in the range of from about 1% to about20% by weight of said composite.
 4. The catalytic composite as set forthin claim 1 in which said alkyl aluminum compound is present in saidcomposite in a mole ratio in the range of from about 0.05:1 to about 6:1moles of alkyl aluminum compound per mole of iron group metal.
 5. Thecatalytic composite as set forth in claim 1 in which the mole ratio ofwater of hydration to iron group metal in said hydrate of an iron groupmetal salt is in a range of from about 0.5:1 to about 6:1 prior toreaction with said alkyl aluminum compound.
 6. The catalytic compositeas set forth in claim 3 in which said iron group metal is nickel.
 7. Thecatalytic composite as set forth in claim 3 in which said iron groupmetal is cobalt.
 8. The catalytic composite as set forth in claim 1 inwhich said alkyl aluminum compound comprises an alkyl aluminum halide.9. The catalytic composite as set forth in claim 8 in which said alkylaluminum halide is dimethyl aluminum chloride.
 10. The catalyticcomposite as set forth in claim 8 in which said alkyl aluminum halide isdiethyl aluminum chloride.
 11. The catalytic composite as set forth inclaim 8 in which said alkyl aluminum halide is diethyl aluminum bromide.12. The catalytic composite as set forth in claim 2 in which saidaluminum halide is aluminum chloride.
 13. The catalytic composite as setforth in claim 2 in which said aluminum halide is aluminum bromide. 14.The catalytic composite as set forth in claim 1 in which said poroussupport comprises alumina.
 15. The catalytic composite as set forth inclaim 1 in which said porous support comprises silica.
 16. The catalyticcomposite as set forth in claim 1 in which said porous support comprisesan aluminosilicate.